Lattice-based dynamic decentralized anonymous credential scheme supporting batch verification

Abstract

Anonymous credentials allow users to obtain credentials while protecting their privacy, which have significant application value in digital identity management systems. Anonymous credential schemes based on post-quantum assumptions mainly rely on a central issuing authority. Once the central server encounters single point of failure, it will cause the entire system to crash. The high computational complexity of credential verification algorithm severely restricts system scalability in high-concurrency identity management scenarios. More critically, existing schemes generally lack non-interactive batch verification algorithm, resulting in linear growth of verification time with the number of credentials when handling large-scale requests. Constructions relying on multiple fixed issuers to issue credentials in a decentralized manner have been proposed. Given that fixed issuers could not adapt to complex and changing network environments, we present a lattice-based decentralized anonymous credential system that supports dynamic changes in issuers to enhance system robustness. By introducing an innovative threshold signature, our system flexibly accommodates the joining or leaving of issuers for various reasons. Meanwhile, the system enables dynamic adjustments of thresholds without reset. By utilizing an efficient cryptographic accumulator, the system supports batch verification of credentials without revealing their contents. Experimental results demonstrate that our system outperforms previous systems in terms of performance. It is worth noting that our batch credential verification algorithm achieves constant time cost, independent of user’s credential size.